<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        function show(){
           return 12;
        }
//        var a=show();
//        alert(a);
      //  alert(show());

        function show1(a,b){
            return a+b;
        }
        alert(show1(4,2));
    </script>
</head>
<body>
<!--一个函数应该只返回一种类型的值-->
</body>
</html>